Seat backs for vehicular seats

ABSTRACT

A seat back for a vehicular seat has a plate member for supporting a back of a pad and an elastic support mechanism for elastically holding the plate member for moving the plate member in a forward and backward with respect to a seat back frame. The plate member includes a first plate portion, a second plate portion positioned on the lower side of the first plate portion, and a third plate portion positioned on the lower side of the second plate portion. The first and third plate portions are more narrow than the second plate portion. The elastic support mechanism includes a rod-shaped elastic bridge member extending horizontally over the seat back frame on the back of the second plate portion. In addition, the elastic bridge member includes a bent portion at the center position as bent along the second plate portion toward the first plate portion.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a seat back for a vehicular seat.

2. Description of the Related Art

The seat back for the vehicular seat generally includes a seat backframe and a pad. Moreover, the seat back of the type having a thin padfurther includes a plate member for supporting the back of the pad, andan elastic support mechanism for holding the plate member elasticallyand movably forward and backward relative to the seat back frame. Theplate member of the prior art is disclosed in U.S. Pat. No. 6,296,308(308 patent), for example. These plate members are formed into asubstantially rectangular shape. And the portion for supporting thelumber of the passenger seated on the vehicular seat is made wider thanthe remaining portions.

However, there is a need in the art for a plate member and an elasticsupport mechanism that provides additional support for a user, thusresulting in a more comfortable use.

SUMMARY OF THE INVENTION

One aspect of the present invention can include a seat back for avehicular seat having a plate member for supporting a back of a pad andan elastic support mechanism for elastically holding the plate memberfor moving the plate member in a forward and backward with respect to aseat back frame. The plate member includes a first plate portion, asecond plate portion positioned on the lower side of the first plateportion, and a third plate portion positioned on the lower side of thesecond plate portion. The first and third plate portions are more narrowthan the second plate portion. The elastic support mechanism includes arod-shaped elastic bridge member extending horizontally over the seatback frame on the back of the second plate portion. In addition, theelastic bridge member includes a bent portion at the center position asbent along the second plate portion toward the first plate portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a seat for a vehicle;

FIG. 2 is a perspective view of a back of a seat back frame, a platemember and an elastic support mechanism;

FIG. 3 is a perspective view of a back of the plate member;

FIG. 4 is a rear view of the plate member;

FIG. 5 is a cross-sectional view taken along line V-V in FIG. 1; and

FIG. 6 is an enlarged view of a back of an elastic bridge member and apart of the plate member near right side of a bent portion of theelastic bridge member.

DETAILED DESCRIPTION OF THE INVENTION

Each of the additional features and teachings disclosed above and belowmay be utilized separately or in conjunction with other features andteachings to provide improved seat backs for vehicular seats.Representative examples of the present invention, which examples utilizemany of these additional features and teachings both separately and inconjunction with one another, will now be described in detail withreference to the attached drawings. This detailed description is merelyintended to teach a person of skill in the art further details forpracticing preferred aspects of the present teachings and is notintended to limit the scope of the invention. Only the claims define thescope of the claimed invention. Therefore, combinations of features andsteps disclosed in the following detailed description may not benecessary to practice the invention in the broadest sense, and areinstead taught merely to particularly describe representative examplesof the invention. Moreover, various features of the representativeexamples and the dependent claims may be combined in ways that are notspecifically enumerated in order to provide additional usefulconfigurations of the present teachings.

A configuration of the present invention is described with reference toFIGS. 1 to 6. As shown in FIG. 1, a vehicular seat 10 comprises a seatcushion 11 for seating a user, and a seat back 1 for supporting the backof the user. Between the seat cushion 11 and the seat back 1, there areinterposed reclining devices 14 for reclining the seat back 1 againstthe seat cushion 11. A headrest 12 for supporting the head of the useris attached to and is vertically movable in relation to the upperportion of the seat back 1.

As shown in FIG. 1, the seat back 1 can include a seat back frame 2, apad 7, a plate member 3 for supporting the back side of the pad 7, andan elastic support mechanism 4 for holding the plate member 3elastically against the seat back frame 2. As shown in FIG. 2, the seatback frame 2 can have a rectangular shape and be composed of left andright side frames 2 a and 2 b, an upper frame 2 c and an under frame 2d.

The upper frame 2 c is equipped with a pair of cylinder portions 2 e, asshown in FIG. 2. The headrest 12 includes stays 12 a (as referred toFIG. 1) so inserted into the cylinder portions 2 e as can be adjusted invertical positions. The pad 7 can be formed of an elastically deformablematerial such as foamed urethane. Moreover, the pad 7 has apredetermined thickness, as shown in FIG. 5, and covers the front sideand the side faces of the seat back frame 2. The pad 7 has its surfacecovered with a surface member 8.

The plate member 3 is made smaller than the seat back frame 2, as shownin FIG. 1, and is arranged on the back side of the pad 7. The platemember 3 is molded of a composite material composed mainly of a resinand glass fibers. The resin may be a polyamide resin such as nylon 6(PA6). The glass fibers have a weight of 10 to 20 wt. % of the totalweight of the composite material. The plate member 3 is formed into aplate shape having a thickness of about 2 mm. As shown in FIG. 3,moreover, the plate member 3 can be defined by plate portions 3 a to 3e, and by having a left-right symmetric shape.

The first plate portion 3 a is arranged at a height approximatelymatching or proximate to a scapulae of an adult user, as shown in FIGS.3 and 4. Moreover, the first plate portion 3 a is shaped on its twotransverse sides so as to avoid the scapulae, and therefore it is morenarrow than the remaining plate portions 3 b to 3 e. The first plateportion 3 a has a width of 40 to 60% of that of the second plateportions 3 b, for example. The third plate portion 3 c is arranged at aheight matching the kidneys of the user. Moreover, the third plateportion 3 c is shaped on its two transverse sides so as to avoid akidney of a user, and therefore it is more narrow than the second plateportion 3 b. The third plate portion 3 c has a width that is 70 to 90%of a width of the second plate portion 3 b, for example.

The fourth plate portion 3 d is arranged at a height approximatelymatching or proximate to the lumbar of the user, thus being wider thanthe remaining plate portions 3 a to 3 c and 3 e. The fourth plateportion 3 d has a width 140 to 160% of a width of the third plateportion 3 c, for example. The fifth plate portion 3 e is arranged at aheight approximately matching or proximate to the pelvis of the user,and is tapered to be narrow in a downward direction.

The plate member 3 has a thoracic vertebra avoiding portion 3 f formedat its widthwise center position, as shown in FIGS. 3 and 4. Thethoracic vertebra avoiding portion 3 f is formed at such a position ofthe backbone of the user as corresponds to the thoracic vertebrae, andis vertically elongated from the lower side portion of the first plateportion 3 a to the upper side portion of the fourth plate portion 3 d.The thoracic vertebra avoiding portion 3 f is wider than the thoracicvertebrae, thus having a width of 40 to 100 mm, preferably 50±10 mm. Thethoracic vertebra avoiding portion 3 f further defines holes 3 f 1 and 3f 2 and a recessed portion 3 f 3.

The open holes 3 f 1 and 3 f 2 are defined at the upper and lowerpositions of the thoracic vertebra avoiding portion 3 f, as shown inFIGS. 3 and 4, and extend through the plate member 3 in the thicknessdirection. The upper open hole 3 f 1 extends from the lower side portionof the first plate portion 3 a to the general center of the second plateportion 3 b. The lower open hole 3 f 2 extends vertically across thethird plate portion 3 c to the upper side portion of the fourth plateportion 3 d.

The recessed portion 3 f 3 is positioned between the open holes 3 f 1and 3 f 2, as shown in FIGS. 3 and 4. The recessed portion 3 f 3 hasslope portions 3 f 6, formed on the two transverse sides, and slopedobliquely backward away from the thoracic vertebrae, and a bottomportion 3 f 7 connecting the slope portions 3 f 6. The recessed portion3 f 3 has a depth of 5-10 mm, for example. The recessed portion 3 f 3 isso positioned on the lower side of the second plate portion 3 b as toconnect the lower left portion and the lower right portion of the secondplate portion 3 b. As a result, the recessed portion 3 f 3 prevents theopen holes 3 f 1 and 3 f 2 from being largely opened to the left andright when the plate member 3 is deformed.

Moreover, the recessed portion 3 f 3 is positioned, as shown in FIG. 2,between elastic bridge members 5 and 6 of the elastic support mechanism4. As a result, in case the plate member 3 receives a strong forcebackward between the elastic bridge members 5 and 6, the open hole 3 f 2can be prevented from being largely opened to the left and right by therecessed portion 3 f 3. As shown in FIGS. 3 and 4, the recessed portion3 f 3 is provided with a through hole 3 f 4 and a rib 3 f 5. The throughhole 3 f 4 is transversely long, and the rib 3 f 5 is transversely longat the upper side position of the through hole 3 f 4.

As shown in FIGS. 3 and 4, ribs 3 g, 3 h and 3 n are formed on the backof the plate member 3. The rib 3 g is formed on the outer periphery ofthe upper side of the plate member 3, that is, on the outer peripheraledges of the first to fourth plate portions 3 a to 3 d. The rib 3 h istransversely extended and formed on the back of the fourth plate portion3 d. As shown in FIG. 2, the lumbar elastic bridge member 6 of theelastic support mechanism 4 is inserted into the ribs 3 h. A gap of20±10 mm is formed between the ribs 3 h and the open hole 3 f 2 so thatthe open hole 3 f 2 has no contact with the ribs 3 h. As a result, theplate member 3 rigidity is enhanced, and the concentration of stress isreduced or eliminated in the vicinity of the end portion of the openhole 3 f 2.

The ribs 3 n are vertically extended, as shown in FIG. 4, and formed onthe two transverse sides of the thoracic vertebra avoiding portion 3 f.The upper end portions of the ribs 3 n reach the ribs 3 g of the firstplate portion 3 a, and the lower end portions extend downward to theribs 3 h.

The fifth plate portion 3 e has a plurality of openings 3 e 1 formed, asshown in FIGS. 3 and 4. These openings 3 e 1 are made transversely long,and are arranged vertically in plurality. Moreover, the fifth plateportions 3 e has no rib formed on its outer periphery. As a result, thefifth plate portion 3 e is made deformable in the thickness directionand light in weight. A pair of pawls 3 e 2 are formed at the lower endportion of the fifth plate portion 3 e. The pawls 3 e 2 can be hooked ona shaft member 14 a, as shown in FIG. 2. The shaft member 14 ainterlocks the left and right reclining devices 14.

As shown in FIG. 2, the elastic support mechanism 4 includes a pair ofthe elastic bridge members 5 and 6, which are horizontally bridged onthe seat back frame 2. The elastic bridge member 5 is an elasticrod-shaped member made of a metal, and is attached to the back of thesecond plate portion 3 b. The elastic bridge member 5 includes a bentportion 5 a at its center. And horizontal portions 5 b and end portions5 c are provided on the two sides of the bent portion 5 a.

As shown in FIG. 2, the end portions 5 c are connected to the sideframes 2 a and 2 b, and are extended obliquely downward. The horizontalportions 5 b extend substantially horizontally from the end portions 5c. The bent portion 5 a is bent, as shown in FIG. 6, along the secondplate portion 3 b and toward the first plate portion 3 a. The bentportion 5 a has left and right rising portions 5 a 1 and a connectingportion 5 a 2. The rising portions 5 a 1 are extended upward from thehorizontal portions 5 b toward the first plate portion 3 a. Theconnecting portion 5 a 2 extends substantially horizontally, andconnects the left and right rising portions 5 a 1.

As a result, the elastic bridge member 5 can elastically support thesecond plate portion 3 b and movably in a forward and backwarddirection. Moreover, the elastic bridge member 5 has the bent portion 5a so that it can support such a force as is applied to the first plateportion 3 a with a torsional force.

On the back of the second plate portion 3 b, as shown in FIGS. 2 and 6,there are formed hook portions 3 j and positioning portions 3 k forholding the elastic bridge member 5. The hook portions 3 j have openingportions 3 j 1, into which the horizontal portions 5 b of the elasticbridge member 5 are inserted from the lower side. The positioningportions 3 k are protruded from the inner sides of the corners of therising portions 5 a 1 and the connecting portion 5 a 2 of the elasticbridge member 5. As a result, the hook portions 3 j and the positioningportions 3 k regulate vertical movements of the elastic bridge member 5.Moreover, the paired positioning members 3 k regulate transversemovements of the elastic bridge member 5. Thus, the elastic bridgemember 5 can be stably held on the plate member 3.

The second plate portion 3 b has erroneous assembly preventingprojections 3 m formed on their backs, as shown in FIGS. 2 and 6. Theerroneous assembly preventing projections 3 m are formed at the lowerside positions of the positioning portions 3 k, thus extending obliquelydownward from the positioning portions 3 k. When the elastic bridgemember 5 is assembled with the second plate portion 3 b, the erroneousassembly preventing projections 3 m can prevent the bent portion 5 afrom coming into the state toward the third plate portion 3 c. Thus, theelastic bridge member 5 can be correctly assembled with the second plateportion 3 b by utilizing the erroneous assembly preventing projections 3m.

As shown in FIG. 2, the elastic bridge member 5 extends across the leftand right ribs 3 n. As a result, the elastic bridge member 5 ispositioned backward of the open hole 3 f 1 by a distance at least equalto the height of the ribs 3 n. In case the plate member 3 is elasticallydeformed, therefore, the elastic bridge member 5 is prevented frompushing the thoracic vertebrae of the user through the open hole 3 f 1.

The elastic bridge member 6 is disposed along the ribs 3 h of the fourthplate portion 3 d, as shown in FIG. 2. The elastic bridge member 6includes a pair of coil springs 6 a and a wire 6 b, as shown in FIGS. 2and 5. The ends of the paired coil springs 6 a are connected to the sideframes 2 a and 2 b. Moreover, a holding portion 6 d for holding theleading end of the wire 6 b, is attached to the other end portion of onecoil spring 6 a. To the other end portion of the other coil spring 6 a,there is attached an outer tube 6 c, into which the wire 6 b isinserted. Moreover, the wire 6 b is tensed between the paired coilsprings 6 a.

The wire 6 b and the outer tube 6 c are arranged in the vehicular seat10, as shown in FIG. 1, and are connected (at one of the end portions)to a take-up portion 13. This take-up portion 13 is mounted on the sideportion of the seat cushion 11, and takes up the wire 6 b with respectto the outer tube 6 c, when clockwise turned on its axis, but releasesthe wire 6 b with respect to the outer tube 6 c when counter-clockwiseturned on its axis. As a result, the wire 6 b between the paired coilsprings 6 a is adjusted on its length by the take-up portion 13.Therefore, the total length of the lumbar elastic bridge member 6 isadjusted by adjusting the length of the wire 6 b.

Here, the plate member 3 is positionally retained, as shown in FIG. 2,at its upper end portion by the elastic bridge member 5 and at its lowerend portion by the pawls 3 e 2. As a result, the plate member 3 issubstantially supported at its front and back positions by the elasticbridge member 5 and the pawls 3 e 2. On the other hand, the coil springs6 a of the lumbar elastic bridge member 6 are attached to the seat backframe 2, thus being positioned on the forward side of the elastic bridgemember 5 and the pawls 3 e 2. As a result, the lumbar elastic bridgemember 6 can be shortened to push the fourth plate portion 3 d forward.Moreover, the lumbar elastic bridge member 6 can be elongated to movethe fourth plate portion 3 d backward. As a result, the elastic bridgemember 5 can deform the plate member 3 to adapt the body shape of theuser.

In the lumbar elastic bridge member 6 thus adjusted in length, the coilspring 6 a is elastically deformed to move the plate member 3 forwardand backward. Moreover, the plate member 3 and the elastic supportmechanism 4 are shielded with a protective plate 9 covering the back ofthe seat back 1, as shown in FIG. 5.

Accordingly, the plate member 3 has the first plate portion 3 a, thesecond plate portion 3 b and the third plate portion 3 c, of which thefirst and third plate portions 3 a and 3 c are made narrower than thesecond plate portion 3 b. The elastic support mechanism 4 has theelastic bridge member 5, and this elastic bridge member 5 has the bentportion 5 a.

In the plate member 3, therefore, the first plate portion 3 a has asmall width so that the area for pushing the scapulae is reduced or theplate member 3 doesn't push the scapulae. Moreover, the third plateportion 3 b has a small width so that the area for pushing the vicinityof the kidneys is reduced. As a result, the force to push the vicinitiesof the scapulae and the kidneys is reduced to improve thecomfortableness of the vehicular seat 10. In the plate member 3,moreover, the second plate portion 3 b has a large width, and issupported by the elastic bridge member 5. As a result, the passenger issupported at positions avoiding the vicinities of the scapulae and thekidneys, so that the comfortableness of the vehicular seat 10 isimproved. On the other hand, the elastic bridge member 5 is provided atits center position with the bent portion 5 a, which is bent toward thefirst plate portion 3 a. As a result, the elastic bridge member 5 cansupport the force applied on the side of the first plate portion 3 a,with its torsional force.

Moreover, the plate member 3 is provided, as shown in FIG. 2, with thefourth plate portion 3 d, which is made wider than the third plateportion 3 c. Moreover, the elastic support mechanism 4 is provided withthe lumbar elastic bridge member 6, which is horizontally bridged overor extended between ends of the seat back frame 2, thereby holding orsupporting the fourth plate portion 3 d. Therefore, the plate member 3has the fourth plate portion 3 d, which is made wide and supported bythe lumbar elastic bridge member 6. As a result, the lumbar of thepassenger can be stably held or supported by the fourth plate portion 3d and the lumbar elastic bridge member 6. As a result, an improvedcomfortableness of the vehicular seat 10 can be obtained.

Moreover, the lumbar elastic bridge member 6 can be adjusted in itslength, as shown in FIG. 5, so that it can adjust the position of thefourth plate portion 3 d forward and backward. As a result, the fourthplate portion 3 d can be adjusted forward and backward according to theposition of the lumbar of the passenger.

While the invention has been described with reference to specificconfiguration, it will be apparent to those skilled in the art that manyalternatives, modifications and variations may be made. Accordingly, thepresent invention is intended to embrace all such alternatives,modifications and variations that may fall within the spirit and scopeof the appended claims. For example, the present invention should not belimited to the representative configuration, but may be modified asdescribed below.

In FIG. 2, the elastic bridge member 5 has the rod shape of a circularsection. However, the elastic member may also have a rod shape of arectangular or polygonal section, or a rod shape of a flat plate.

In FIG. 3, the second plate portion 3 b is provided on its back with thepaired hook portions 3 j and the paired positioning portions 3 k.However, the configuration may also be modified to have one of left orright hook portion 3 j and the paired positioning portions 3 k. In thisconfiguration, too, the elastic bridge member 5 can be positionedvertically and transversely.

In FIG. 5, the lumbar elastic bridge member 6 is adjusted in its lengthto adjust the position of the fourth plate portion 3 d forward andbackward. However, another configuration may also be modified into apositionally unadjustable one, in which the lumbar elastic bridge memberis identical to the rod-shaped elastic bridge member 5.

1. A seat back for a vehicular seat comprising: a plate member forsupporting a back of a pad; and an elastic support mechanism capable ofelastically supporting the plate member for moving the plate memberforward and backward with respect to a seat back frame, wherein theplate member includes a first plate portion positioned to be proximate ascapulae of a user seated on the vehicular seat, a second plate portionpositioned on the lower side of the first plate portion, and a thirdplate portion positioned on the lower side of the second plate portionand positioned to be proximate a kidney of the user, wherein the firstand third plate portions are more narrow than the second plate portion,wherein the elastic support mechanism includes a rod-shaped elasticbridge member extending horizontally over the seat back frame on theback of the second plate portion, and wherein the elastic bridge memberincludes a bent portion at a center position, the bent portion beingpositioned along the second plate portion toward the first plateportion.
 2. The seat back as in claim 1, wherein the plate memberincludes a fourth plate portion positioned to be proximate a lumbar ofthe user and the lower side of the third plate portion, wherein thefourth plate portion is wider than the third plate portion, and whereinthe elastic support mechanism includes a lumbar elastic bridge memberextending horizontally over the seat back frame for holding the fourthplate portion.
 3. The seat back as in claim 2, wherein the lumbarelastic bridge member is longitudinally adjustable and capable ofadjusting the fourth plate portion in a forward and backward direction.4. The seat back as in claim 1, wherein the rod-shaped elastic bridgemember has left and right horizontal portions extending substantiallyhorizontally from left and right end portions of the bent portion,wherein the bent portion has left and right rising portions extendedtoward the first plate portion from the left and right horizontalportions, and a connecting portion for connecting the left and rightrising portions, and wherein the second plate portion has left and righthook portions to be engaged the horizontal portions from the lower side,and left and right positioning portions protruded at the corners of therising portions and the connecting portion, so that the elastic bridgemember is held by the hook portions and the positioning portions.
 5. Theseat back as in claim 4, wherein the back of the second plate portionhas an erroneous assembly preventing projection at the lower position ofthe positioning portion, further wherein the erroneous assemblypreventing projection is capable of preventing the elastic bridge memberfrom being assembled with the second plate portion while the bentportion of the elastic bridge member is directed toward the third plateportion.
 6. A vehicular seat comprising: a seat back including: a frame;a plate member connected to the frame, the plate member including: afirst plate portion positioned to be proximate a scapulae of a user, asecond plate portion positioned on the lower side of the first plateportion; and a third plate portion positioned on the lower side of thesecond plate portion and positioned to be proximate a kidney of theuser; wherein the first and third plate portions are more narrow thanthe second plate portion; an elastic support mechanism capable ofelastically supporting the plate member for moving the plate memberforward and backward with respect to the frame, wherein the elasticsupport mechanism includes a rod-shaped elastic bridge member extendinghorizontally over the frame on the back of the second plate portion,further wherein the elastic bridge member includes a bent portion at acenter position, the bent portion being positioned along the secondplate portion toward the first plate portion.
 7. The seat as in claim 6,wherein the plate member includes a fourth plate portion positioned tobe proximate a lumbar of the user and the lower side of the third plateportion.
 8. The seat as in claim 7, wherein the fourth plate portion iswider than the third plate portion.
 9. The seat as in claim 8, whereinthe elastic support mechanism includes a lumbar elastic bridge memberextending horizontally over the frame for supporting the fourth plateportion.
 10. The seat as in claim 9, wherein the lumbar elastic bridgemember is longitudinally adjustable and capable of adjusting the fourthplate portion in a forward and backward direction.
 11. The seat back asin claim 6, wherein the rod-shaped elastic bridge member has left andright horizontal portions extending substantially horizontally from leftand right end portions of the bent portion.
 12. The seat as in claim 11,wherein the bent portion has left and right rising portions extendedtoward the first plate portion from the left and right horizontalportions, and a connecting portion for connecting the left and rightrising portions.
 13. The seat back as in claim 12, wherein the secondplate portion has left and right hook portions capable of engagement thehorizontal portions from the lower side, and left and right positioningportions protruded at the corners of the rising portions and theconnecting portion, so that the bridge member is supported by the hookportions and the positioning portions.
 14. The seat back as in claim 13,wherein the back of the second plate portion has an erroneous assemblypreventing projection at the lower position of the positioning portion,further wherein the erroneous assembly preventing projection is capableof preventing the elastic bridge member from being assembled with thesecond plate portion while the bent portion of the elastic bridge memberis directed toward the third plate portion.